Year	% of land area
1961	2.57973780702195
1962	2.5164498468029537
1963	2.5013812848460497
1964	2.5174544176000806
1965	2.6842131699231504
1966	2.7927068160128585
1967	2.813802802752524
1968	2.813802802752524
1969	2.8479582098548395
1970	2.855994776231855
1971	2.8650359134059973
1972	2.868049625797378
1973	2.868049625797378
1974	2.855994776231855
1975	2.83791250188357
1976	2.742478276156512
1977	2.647044050429454
1978	2.5516098247023957
1979	2.4581847405695916
1980	2.4561755989753378
1981	2.4792807273092574
1982	2.4564166959666482
1983	2.4458687025968153
1984	2.469496207745241
1985	2.508413280425938
1986	2.578733236224823
1987	2.5586418202822845
1988	2.5927972273846
1989	2.5827515194133306
1990	2.660103470792104
1991	2.6550806168064693
1992	3.0099753880154703
1993	3.0289617760811693
1994	3.0264302576724096
1995	3.298005926967703
1996	3.1909789542418
1997	3.2597518710131097
1998	3.2745190617308753
1999	3.4989200863930883
2000	3.3060424933447186
2001	3.3532573208096843
2002	3.4396504093625997
2003	3.4245818474056957
2004	3.4938972324074538
2005	3.5391029182781657
2006	3.5491486262494347
2007	3.5541714802350697
2008	3.5581897634235777
2009	3.7058616706012355
2010	3.687779396252951
2011	3.6365462855994775
2012	3.712893666181124
2013	3.7480235069566525
2014	3.7321713797779896
2015	3.8071998593600886
2016	3.750831684162941
2017	3.8545068059671506
2018	3.880656989301321
2019	3.9399266663318095
2020	3.989150635391029
2021	4.049424883218645